1. Field of the Invention
The present invention relates to a one component room temperature curable sealant composition. Particularly, it relates to a one component room temperature curable sealant composition which is useful as a sealing material, an adhesive or an injection molding material and which exhibits good adhesion to various substrates including metal, glass and coated steel sheets and plastics such as a vinyl chloride resin, an acrylic resin or a styrol resin, without requiring a primer coating. More particularly, the composition of the present invention is widely useful as a sealant for various applications, for instance, for sealing the joint of interior or exterior building structures, repairing cracks in mortar or concrete structures, fixing the windshields of automobiles, sealing seams of joined steel sheets, etc., and it can advantageously be applied directly to substrate surfaces such as metal, glass, melamine and acrylic resin surfaces without employing a primer.
2. Description of the Prior Art
As a one component room temperature curable sealant, a silicone or polyurethane sealant is well known. The silicone sealant has advantages such that it has good weather resistance and heat resistance, and its curing speed is high and yet its storage stability is good. On the other hand, it has disadvantages such that a coating composition is hardly applied onto a cured silicone sealant, and it is likely to stain stone materials. Whereas the polyurethane sealant has advantages such that it is superior to the silicone sealant in the curing properties, and it has good comparability with a coating composition and its production costs are relatively low. On the other hand, the polyurethane sealant has drawbacks such that it is inferior in the weather resistance and heat resistance, and its storage stability tends to be poor when it is made to have a high curing speed.
Under the circumstances, an attention has been drawn to the a polyether polymer having hydrolyzable silicone functional groups, as a prospective material having advantages of both the silicone and polyurethane sealants and complementing the disadvantages thereof.
Heretofore, with respect to a one component room temperature curable composition for a sealing material, a coating material, an adhesive and an injection molding material, there has been proposed a composition comprising (A) an addition product of a polyether urethane prepolymer having terminal isocyanate groups and .gamma.-amino-propyltrimethoxysilane and (B) a small amount of N-.beta.(aminoethyl)-.gamma.-amino propyltrimethoxysilane (Japanese Examined Patent Publication No. 5061/1978) as the material containing as the basic component a polyether polymer having a hydrolyzable silicone functional group as its terminal group.
Further, there has been proposed a composition containing as the main component an oxypropylene polymer having a terminal silylether group represented by the formula: ##STR5## (Japanese Unexamined Patent Publications No. 156599/1975 and No. 73998/1977).
However, these compositions had a disadvantage such that they are hardly bonded to the above-mentioned substrates without a primer coating.
As additives to improve the adhesion of the polyether polymer having at its terminal a hydrolyzable silicone functional group, there have been known a phenol resin, an epoxy resin (Japanese Unexamined Patent Publications No. 73729/1977 and No. 156599/1975), a polyisocyanate compound having an active isocyanate group (Japanese Unexamined Patent Publication No. 73729/1980) and a triazine ring compound (Japanese Unexamined Patent Publication No. 34154/1982). However, these additives do not necessarily provide adequate effectiveness and have drawbacks such that they are inferior in the water-resistant bonding and durability, whereby there have been problems such that stabilized bond strength is hardly obtainable due to restrictions with respect to the curing catalyst or the mixing conditions, and that no adequate storage stability is obtainable as a one component sealant.
Further, when N-.beta.(aminoethyl)-.gamma.-aminopropyltrimethoxysilane is added to the above polymer as proposed in Japanese Examined Patent Publication No. 5061/1978, the adhesion to glass or aluminum can be improved, but the water resistance tends to be poor, whereby no stabilized bond strength will be obtained.